Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

torvalds · torvalds · commit e4880bc5dfb1 · 2017-11-06T12:26:49.000-08:00
Pull workqueue fix from Tejun Heo:
 "Another fix for a really old bug.

  It only affects drain_workqueue() which isn't used often and even then
  triggers only during a pretty small race window, so it isn't too
  surprising that it stayed hidden for so long.

  The fix is straight-forward and low-risk. Kudos to Li Bin for
  reporting and fixing the bug"

* 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Fix NULL pointer dereference
diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h
@@ -10,6 +10,7 @@
 
 #include <linux/workqueue.h>
 #include <linux/kthread.h>
+#include <linux/preempt.h>
 
 struct worker_pool;
 
@@ -60,7 +61,7 @@ struct worker {
  */
 static inline struct worker *current_wq_worker(void)
 {
-	if (current->flags & PF_WQ_WORKER)
+	if (in_task() && (current->flags & PF_WQ_WORKER))
 		return kthread_data(current);
 	return NULL;
 }

Original file line number	Diff line number	Diff line change
`@@ -10,6 +10,7 @@`
`10`	`10`
`11`	`11`	`#include <linux/workqueue.h>`
`12`	`12`	`#include <linux/kthread.h>`
	`13`	`+#include <linux/preempt.h>`
`13`	`14`
`14`	`15`	`struct worker_pool;`
`15`	`16`
`@@ -60,7 +61,7 @@ struct worker {`
`60`	`61`	`*/`
`61`	`62`	`static inline struct worker *current_wq_worker(void)`
`62`	`63`	`{`
`63`		`- if (current->flags & PF_WQ_WORKER)`
	`64`	`+ if (in_task() && (current->flags & PF_WQ_WORKER))`
`64`	`65`	`return kthread_data(current);`
`65`	`66`	`return NULL;`
`66`	`67`	`}`